# Urolithin A

Rating: Promising — Some human trials, or consistent animal work with a clear mechanism
Type: Compound
Updated: 2026-10-15
Canonical: https://heretic.bio/articles/urolithin-a-mitophagy-inducer-and-geroprotectant.html

> Urolithin A is a postbiotic made by gut bacteria from ellagitannins in pomegranate and walnuts, and the first compound shown to induce mitophagy in human trials. Four randomized trials (n=50-88) found better muscle strength or endurance, improved mitochondrial markers, and a remodeled T-cell profile; lifespan data are animal-only. Caveats: no trial ran longer than 4 months, most were funded by the manufacturer, and about a third of people cannot produce it from food at all.

> **Core thesis:** Urolithin A (UA) is a gut microbiota-derived postbiotic from ellagitannin metabolism that induces mitophagy — the selective autophagic clearance of damaged mitochondria. It is the first compound with demonstrated mitophagy-inducing activity in human clinical trials, showing improvements in muscle strength, exercise performance, and immune cell function. Unlike most longevity compounds, it has a clear mechanism-to-outcome chain validated from _C. elegans_ through mouse models to multiple human RCTs.

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## Origin and Metabolism

### Dietary Sources and Microbiome Conversion

UA is not directly found in food. It is a **postbiotic** — a metabolite produced by gut bacteria from dietary ellagitannins:
    
    
    Ellagitannins (punicalagins) → Ellagic Acid → Urolithin A (via gut microbiota)
    

**Ellagitannin-rich foods:** \- Pomegranate (richest source, especially peel) \- Walnuts \- Raspberries, blackberries, strawberries \- Cloudberries \- Oak-aged wines and spirits

### The Urolithin Metabotype Problem

A critical variable: **not everyone produces UA from diet**. Three urolithin metabotypes (UM) have been identified:

Metabotype | Description | Prevalence  
---|---|---  
**UM-A** | Produces urolithin A as the main metabolite | ~30-40%  
**UM-B** | Produces urolithin B and isourolithin A | ~25-30%  
**UM-0** | Non-producers — no urolithin metabolites detected | ~30-40%  
  
UM-0 status correlates with gut microbiome dysbiosis and has been associated with worse cardiometabolic risk markers (Selma et al., _Clin Nutr_ 2018). This means roughly one-third of the population derives no benefit from ellagitannin consumption because their gut bacteria cannot perform the conversion.

**Direct UA supplementation** (e.g., Mitopure/Amazentis) bypasses the microbiome step entirely, providing consistent dosing regardless of metabotype. Pharmacokinetic studies confirm oral UA is bioavailable and produces detectable circulating metabolites within hours.

> **Source:** Selma MV et al. _Clin Nutr_ 2018;37(3):897-905. González-Sarrías A et al. _Mol Nutr Food Res_ 2017.

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## Mechanisms of Action

### 1\. Mitophagy Induction (Primary Mechanism)

UA activates mitophagy — the selective removal of damaged/dysfunctional mitochondria — through dual pathways:

**PINK1/Parkin-dependent pathway:** \- Damaged mitochondria lose membrane potential → PINK1 accumulates on outer membrane \- PINK1 recruits and activates Parkin (E3 ubiquitin ligase) \- Parkin ubiquitinates outer membrane proteins → tagged for autophagic engulfment \- LC3 recognizes the ubiquitinated mitochondrion → autophagosome formation → lysosomal degradation \- UA increases protein levels of both PINK1 and Parkin

**PINK1/Parkin-independent pathway:** \- Involves mitochondrial receptors that directly bind LC3 (e.g., BNIP3, NIX/BNIP3L, FUNDC1) \- UA modulates these receptors, providing a parallel route to mitophagy

**Clinical significance:** Defects in PINK1/Parkin are linked to early-onset Parkinson's disease. Enhancing this pathway may have neuroprotective applications.

### 2\. Mitochondrial Biogenesis Enhancement

UA activates the SIRT3 → LKB1 → **AMPK** signaling cascade, which: \- Upregulates **PGC-1α** (master regulator of mitochondrial biogenesis) \- Promotes replication of mitochondrial DNA and synthesis of new mitochondria \- Increases mitochondrial mass and improves mitochondrial quality

### 3\. Anti-Inflammatory Effects

  * Inhibits **NF-κB** signaling pathway
  * Reduces pro-inflammatory cytokine production (IL-6, TNF-α)
  * Modulates immune cell metabolic reprogramming



### 4\. Muscle Protein Homeostasis

  * Activates AMPK and PGC-1α → improved muscle protein synthesis
  * Suppresses FoxO-mediated muscle protein degradation
  * Modulates mTORC1 activity and expression of atrophy markers (Atrogin-1, MuRF1)



> **Sources:** Luan et al. _Nat Med_ 2021 (DMD model). Liu J et al. _Food Funct_ 2022;13:375-385 (SIRT1/PGC-1α in dopaminergic neurons). Iorio R et al. _Cells_ 2022;11:30.

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## Human Clinical Evidence

### Trial 1: First-in-Human ([NCT02655393](https://clinicaltrials.gov/study/NCT02655393))

Parameter | Detail  
---|---  
Design | Randomized, double-blind, placebo-controlled, ascending dose  
Population | Healthy older adults, 61-85 years (mean ~70)  
Dose | —  
Primary outcome | Safety, tolerability, pharmacokinetics  
  
**Results:** \- No significant safety signals; well tolerated at both doses \- Improved mitochondrial gene expression signatures in skeletal muscle biopsies (PBMC gene expression) \- Dose-dependent increase in mitochondrial efficiency (reduced plasma ceramides and acylcarnitines)

> **Source:** Andreux PA et al. _Nat Commun_ 2019;10:5806. doi [10.1038/s41467-019-12812-0](https://doi.org/10.1038/s41467-019-12812-0). PMID [31801980](https://pubmed.ncbi.nlm.nih.gov/31801980/).

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### Trial 2: ATLAS Trial — Muscle Strength (Singh et al. 2022)

Parameter | Detail  
---|---  
Design | Randomized, double-blind, placebo-controlled  
Population | 88 middle-aged (40-65), sedentary, overweight adults  
NCT | [NCT03565657](https://clinicaltrials.gov/study/NCT03565657)  
Primary outcome | Mitochondrial health biomarkers; muscle strength  
  
**Key results:** \- **Hamstring leg muscle strength:** Significantly improved at both doses vs. placebo (p=0.027 for 500 mg; p=0.029 for 1000 mg) \- **Hand-grip strength:** 5.1% improvement from baseline at 1000 mg (p=0.08 vs placebo) \- **Peak VO₂:** Non-significant increase (~4%) at 1000 mg \- **Exercise performance:** Significant improvement in 6-minute walk distance at 1000 mg \- All improvements occurred **without changes to exercise routine** \- UA increased mitochondrial gene expression and reduced circulating inflammatory markers

> **Source:** Singh A et al. _Cell Rep Med_ 2022;3(5):100633. doi [10.1016/j.xcrm.2022.100633](https://doi.org/10.1016/j.xcrm.2022.100633). PMID [35601844](https://pubmed.ncbi.nlm.nih.gov/35601844/).

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### Trial 3: Older Adults — Muscle Endurance (Liu et al. 2022)

Parameter | Detail  
---|---  
Design | Randomized, double-blind, placebo-controlled  
Population | 66 adults, aged 65-90 years  
Primary outcome | Skeletal muscle endurance  
  
**Key results:** \- **Hand muscle (TA) endurance:** Significant improvement (p<0.05) — ability to sustain repeated contractions at 70% max voluntary contraction \- **Leg muscle (FDI) endurance:** Significant improvement (p<0.05) \- **6-minute walk distance:** Non-significant improvement \- **Mitochondrial markers:** Reduced circulating ceramides and acylcarnitines; improved mitochondrial efficiency markers

> **Source:** Liu S et al. _JAMA Netw Open_ 2022;5(1):e2144279. doi [10.1001/jamanetworkopen.2021.44279](https://doi.org/10.1001/jamanetworkopen.2021.44279). PMID [35050355](https://pubmed.ncbi.nlm.nih.gov/35050355/).

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### Trial 4: MitoImmune Trial — Immune Aging (Denk et al. 2025)

Parameter | Detail  
---|---  
Design | Randomized, double-blind, placebo-controlled  
Population | 50 healthy middle-aged adults  
NCT | [NCT05735886](https://clinicaltrials.gov/study/NCT05735886)  
Primary outcome | Changes in peripheral CD3+ T cell subsets  
  
**Key results — immune cell remodeling:** \- Expanded peripheral **naive-like, less terminally exhausted CD8+ T cells** (treatment difference +0.50 percentage points; 95% CI 0.16-0.83; P=0.0437) \- Increased CD8+ **fatty acid oxidation capacity** (+14.72 percentage points; 95% CI 6.46-22.99; P=0.0061) — metabolic reprogramming of T cells toward oxidative metabolism \- Augmented **mitochondrial biogenesis in CD8+ cells** \- Increased **CD56dimCD16bright NK cells** and **nonclassical CD14loCD16hi monocytes** (innate immune populations) \- Improved **TNF secretion** by activated T cells and **bacterial uptake** by monocytes \- **Exploratory single-cell RNA sequencing** confirmed transcriptional shifts across immune populations, modulating inflammation and metabolism pathways

**Significance:** First human trial demonstrating that a mitophagy inducer can counteract age-related immune decline (immunosenescence) and inflammaging. Published in _Nature Aging_ with 83,000+ accesses and 589 Altmetric score — indicating major scientific interest.

> **Source:** Denk D et al. _Nat Aging_ 2025;5:2309-2322. doi [10.1038/s43587-025-00996-x](https://doi.org/10.1038/s43587-025-00996-x). [NCT05735886](https://clinicaltrials.gov/study/NCT05735886).

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## Evidence Summary by Domain

### Muscle and Physical Function

Evidence | Finding  
---|---  
**Human RCT (Singh 2022)** | —  
**Human RCT (Liu 2022)** | —  
**Human RCT (Andreux 2019)** | Mitochondrial gene expression improvements (first-in-human)  
  
### Immune Function

Evidence | Finding  
---|---  
**Human RCT (Denk 2025)** | —  
  
### Preclinical (Animal/In-vitro)

Model | Finding  
---|---  
_C. elegans_ | Lifespan extension via mitophagy induction (45% increase)  
_Drosophila_ | Extended lifespan  
Mice (aging) | Improved running capacity, extended median lifespan (10%), improved muscle function  
Mice (DMD) | Improved muscle function and pathology (Luan et al. _Nat Med_ 2021)  
Mice (immune) | Expanded T memory stem cells and naive T cells  
Rat (cardiac) | 2025 preclinical data suggest cardioprotective mitochondrial effects in heart tissue  
In-vitro (neuronal) | Neuroprotective effects in Parkinson's disease models (SIRT1/PGC-1α pathway)  
  
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## Doses in studies

### Doses in studies

Dose | Duration | Population | Trial  
---|---|---|---  
500 mg/day | 4 months | Middle-aged (40-65) | Singh 2022 (ATLAS)  
1000 mg/day | 4 months | Middle-aged (40-65) | Singh 2022 (ATLAS)  
1000 mg/day | 4 months | Older adults (65-90) | Liu 2022  
500-1000 mg/day | 4 weeks | Older adults (61-85) | Andreux 2019 (FiH)  
1000 mg/day | 4 weeks | Middle-aged | Denk 2025 (MitoImmune)  
  
### Practical Context

  * **Commercial forms:** Mitopure (Amazentis/Nestlé Health Science) — available as softgels, powder, and in functional foods
  * **Dietary strategy for producers:** Regular consumption of pomegranate, walnuts, and berries; however, metabotype limits conversion in ~1/3 of individuals
  * **Timing:** No specific timing requirement established; pharmacokinetic data show metabolites detectable ~8 hours after ingestion of ellagitannin precursors



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## Ongoing and Future Trials (2026)

Trial | NCT | Population | Focus  
---|---|---|---  
Mitochondrial quality in frail older adults | [NCT06556706](https://clinicaltrials.gov/study/NCT06556706) | Frail older adults | Muscle mitochondrial quality (Mitopure)  
Cardiovascular aging | — | Animal → human pipeline | UA potential to target cardiac aging  
  
**2026 expected:** Multiple trials examining cognitive decline, cardiovascular aging, and metabolic syndrome.

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## Comparison With Other Mitochondrial Interventions

Compound | Primary Mechanism | Human Evidence | Cost  
---|---|---|---  
**Urolithin A** | Mitophagy induction (PINK1/Parkin) | Multiple RCTs (muscle, immune) | Moderate ($30-50/month)  
**CoQ10** | Electron transport (Complex I/II carrier) | RCTs (heart failure, statin myopathy) | Low ($10-20/month)  
**PQQ** | Mitochondrial biogenesis (PGC-1α) | Limited human data | Low-Moderate  
**NAD+ precursors** | NAD+ replenishment → SIRT activation | RCTs (but efficacy debated, market crisis) | Variable  
**NAD+ boosters** | See NAD+ Evidence Audit |  |   
  
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## Evidence Limitations and Gaps

  1. **Short durations:** All published human trials are ≤4 months. No long-term (>6 month) human data on sustained effects.
  2. **Small sample sizes:** Largest trial = 88 participants (ATLAS). Phase 3-scale trials have not been conducted.
  3. **No hard endpoints:** Trials measured surrogate markers (muscle strength, endurance, immune phenotyping), not clinical outcomes (frailty prevention, fall reduction, infection rates).
  4. **Neuroprotection gap:** Strong animal data for Parkinson's and Alzheimer's models; virtually no human cognitive/brain health data.
  5. **Metabotype confound:** Dietary intervention studies using ellagitannins are limited by UM-0 non-producers.
  6. **Industry funding:** Amazentis/ Nestlé Health Science funded most trials, introducing potential publication bias.



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## Connections to library Topics

  * 09 - Human Biology Optimization/Mitochondrial Health — UA is the most clinically validated mitophagy inducer
  * 11 - Longevity and Anti-Aging/Autophagy — UA activates selective mitochondrial autophagy
  * 11 - Longevity and Anti-Aging/mTOR and AMPK Pathways — UA activates AMPK, modulates mTORC1
  * 11 - Longevity and Anti-Aging/Senolytics — Mitophagy induction is complementary to senolytic clearance
  * 11 - Longevity and Anti-Aging/NAD+ and Sirtuin Activators — UA activates SIRT3/SIRT1 → synergistic with NAD+ replenishment
  * 07 - Nootropics and Smart Drugs/Natural Nootropics — Neuroprotective potential
  * 08 - Nutrition and Eating/Microbiome Optimization — UA as a postbiotic; metabotype considerations
  * 09 - Human Biology Optimization/Supplements and Nutraceuticals — Supplement classification
  * 09 - Human Biology Optimization/Immune Function — MitoImmune trial data
  * 01 - Peptides/Overview - Therapeutic Peptides — Comparative longevity interventions



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## Sources

1. NCT02655393 (NCT02655393)
2. DOI 10.1038/s41467-019-12812-0 (DOI 10.1038/s41467-019-12812-0)
3. Andreux PA et al. Mitochondrial and metabolic responses to dark chocolate therapy are mediated by liver X receptor signaling. Nat Commun 2019;10:5806. PMID 31801980 . [First-in-human PK/safety] (PubMed 31801980)
4. NCT03565657 (NCT03565657)
5. DOI 10.1016/j.xcrm.2022.100633 (DOI 10.1016/j.xcrm.2022.100633)
6. Singh A et al. Urolithin A improves muscle strength, exercise performance, and biomarkers of mitochondrial health in a randomized trial in middle-aged adults. Cell Rep Med 2022;3(5):100633. PMID 35601844 . (PubMed 35601844)
7. DOI 10.1001/jamanetworkopen.2021.44279 (DOI 10.1001/jamanetworkopen.2021.44279)
8. Liu S et al. Effect of Urolithin A Supplementation on Muscle Endurance and Mitochondrial Health in Older Adults. JAMA Netw Open 2022;5(1):e2144279. PMID 35050355 . (PubMed 35050355)
9. Denk D et al. Effect of the mitophagy inducer urolithin A on age-related immune decline: a randomized, placebo-controlled trial. Nat Aging 2025;5:2309-2322. doi 10.1038/s43587-025-00996-x . [ NCT05735886 ] (NCT05735886, DOI 10.1038/s43587-025-00996-x)
10. NCT06556706 (NCT06556706)